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A spectrum of Comet 46P (Wirtanen) with the ALPY600.
The raw spectrum image before sky background subtraction. Note as well as the comet spectrum, the bright Na D line from local light pollution and other auroral lines from natural airglow
The coma extended beyond the length of the slit so a separate sky spectrum was recorded and subtracted
The Spectrum of the bright central region is dominated by the scattered light from the sun while the spectrum of the extended coma is mainly emission from excited molecules such as CN (The very bright line in the UV), C3, C2 (The Swan bands which give the coma its blue green colour) and NH2
By removing the emission component from the spectrum of the central region and dividing it by the spectrum of a sunlike star recorded the same evening, the reflectance spectrum of the dust can be extracted
Just to let you know that the archetypal long period variable star Mira (omicron Ceti) is now nearing its predicted maximum (December 2018) and has reached naked eye visibility. Enjoy!
The November edition of the Binocular Sky Newsletter is ready. As well as the usual overview of DSOs, variable and double stars, this month we have:
* Uranus still available
* Comet 46P
* Mira brightening
* Asteroid occultation for southern England
So grab those binocs (or small telescope) and enjoy the glories that the night sky has to share with us.
To pick up your free copy, just head over to http://binocularsky.com and click on the Newsletter tab. You can also subscribe (also free) and have it emailed each month.